Physical models of vascular systems are being used extensively in our laboratory to study a variety of phenomena related to hemodynamics. During the past year, efforts have been directed to projects in the following categories: (1) a study of intra-arterial drug delivery, using a glass model of the pelvic arteries; (2) a study of the effect of fluid shear on the adhesion of monocytes onto cultured endothelial cells; (3) numerical analysis of flow characteristics in branching vessels; (4) investigation of mechanical strength of several types of cardiovascular stents; and (5) study of the injection characteristics and mixing properties of several angiographic catheters, using a glass model of the human aorta.